Method for forming via hole and trench for dual damascene interconnection

CLAIM OF PRIORITY

0001This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from two applications for METHOD FOR FABRICATING THE VIA HOLE AND TRENCH FOR DUAL DAMASCENE INTERCONNECTION filed in the Korean Industrial Property Office on Dec. 31, 2003 and assigned Ser. Nos. 10-2003-0101800 and 10-2003-0101801.

BACKGROUND

0002(a) Technical Field

0003The present invention relates to a method for forming a metal interconnection of a semiconductor device, and more particularly to a method for forming a via hole and a trench for a dual damascene interconnection.

0004(b) Description of Related Art

0005The introduction of a copper interconnection having an electrical characteristic superior to aluminum (Al) or tungsten (W) has resulted in the use of a dual damascene process for overcoming the difficulty in dry etching copper. In the dual damascene process, a via hole and a trench are first formed, the via hole and the trench are filled with a copper film, and then a planarization process is performed.

0006<figref idref="DRAWINGS">FIGS. 1A and 1B</figref> are sectional views illustrating a method for forming a via hole and a trench for a conventional dual damascene interconnection. <figref idref="DRAWINGS">FIGS. 2 and 3</figref> are sectional views illustrating problems of the method illustrated in <figref idref="DRAWINGS">FIGS. 1A and 1B</figref>.

0007Referring to <figref idref="DRAWINGS">FIG. 1A</figref>, first, an etch stop film <b>110</b> and an inter-metal insulating film <b>120</b> are sequentially formed on a lower metal film <b>100</b>. Subsequently, a via hole <b>130</b> is formed by performing an etching process using a mask pattern for via hole formation. Next, a bottom antireflective coating (BARC) film <b>140</b> is formed on an entire surface in such a manner that via hole <b>130</b> is completely filled with BARC film <b>140</b>. Then a mask pattern <b>150</b> for trench formation is formed on BARC film <b>140</b>.

0008Next, as shown in <figref idref="DRAWINGS">FIG. 1B</figref>, exposed portions of BRAC film <b>140</b> and inter-metal insulating film <b>120</b> are etched up to a certain depth to form a trench <b>170</b> by performing an etching process using mask pattern <b>150</b> for trench formation as an etch mask.

0009As shown in <figref idref="DRAWINGS">FIG. 2</figref>, however, BARC film <b>140</b> has poor flatness due to via hole <b>130</b>, which may result in misalignment in a subsequent photolithography process. In addition, a void <b>160</b> may be generated within via hole <b>130</b>. In this case, the etching process for forming trench <b>170</b> can generate a fence, as denoted by reference numeral “a.”

0010<figref idref="DRAWINGS">FIG. 4</figref> is a flow chart illustrating an example of a method for forming a via hole and a trench for another conventional dual damascene interconnection for overcoming the above problem. <figref idref="DRAWINGS">FIGS. 5 to 7</figref> are sectional views illustrating steps in <figref idref="DRAWINGS">FIG. 4</figref>.

0011Referring to <figref idref="DRAWINGS">FIGS. 4 and 5</figref>, after an etch stop film <b>210</b> and an inter-metal insulating film <b>220</b> are sequentially formed on a lower metal film <b>200</b>, a via hole <b>230</b> is formed in inter-metal insulating film <b>220</b>, exposing a portion of a surface of etch stop film <b>210</b>. (Step <b>410</b>.) Next, a photoresist film <b>240</b> is formed on an entire surface and filled in via hole <b>130</b> (Step <b>420</b>). Next, as shown in <figref idref="DRAWINGS">FIG. 6</figref>, a recess process for photoresist film <b>240</b> is performed. (Step <b>430</b>.)

0012Subsequently, as shown in <figref idref="DRAWINGS">FIG. 7</figref>, after a back side cleaning process is performed (Step <b>440</b>), a BARC film <b>250</b> is formed on an entire surface (Step <b>450</b>). In addition, a mask pattern <b>260</b> for trench formation is formed on BARC film <b>250</b> (Step <b>460</b>).

0013Thereafter, at Steps <b>470</b> and <b>480</b>, a trench is formed by performing an etching process using mask pattern <b>260</b>. Mask pattern <b>260</b> for trench formation and BARC film <b>250</b> are sequentially removed, as is photoresist film <b>240</b> within via hole <b>230</b>. In addition, the portion of etch stop film <b>210</b> exposed through via hole <b>230</b> is removed to form a via hole and a trench for a dual damascene interconnection.

0014A problem with the method described above in <figref idref="DRAWINGS">FIGS. 4-7</figref> is that semiconductor device fabrication apparatuses must be used alternately in order to perform the above conventional method. More specifically, Steps <b>410</b> and <b>420</b> must be performed in a photography apparatus, Step <b>430</b> must be performed in an asher apparatus, Step <b>440</b> must be performed in a cleaning chamber, and Steps <b>470</b> and <b>480</b> must be performed in the photography apparatus again.

0015Accordingly, the conventional method has poor efficiency due to a long process time. Particularly, surface roughness in the ashing process is increased and there are detects due to remaining polymer.

SUMMARY OF THE INVENTION

0016A method for forming a via hole and a trench for a dual damascene interconnection, comprises: forming a via hole through an inter-metal insulating film to expose a portion of a surface of an etch stop film on a lower metal film; forming a photoresist film on an entire surface of the resultant structure and in the via hole is filled with the photoresist film; exposing a top surface and a side surface of the inter-metal insulating film by recessing the photoresist film using a development process for the photoresist film; forming a bottom antireflective coating film on the exposed surfaces of the inter-metal insulating film and the photoresist film; forming a mask pattern on the bottom antireflective coating film; forming a trench by an etching process using the mask pattern as an etch mask; and completely removing the photoresist film within the via hole.

BRIEF DESCRIPTION OF THE DRAWINGS

0017The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention:

0018<figref idref="DRAWINGS">FIGS. 1A and 1B</figref> are sectional views illustrating an example of a method for forming a via hole and a trench for a conventional dual damascene interconnection;

0019<figref idref="DRAWINGS">FIGS. 2 and 3</figref> are sectional views illustrating problems of the method illustrated in <figref idref="DRAWINGS">FIGS. 1A and 1B</figref>;

0020<figref idref="DRAWINGS">FIG. 4</figref> is a flow chart illustrating an example of a method for forming a via hole and a trench for another conventional dual damascene interconnection for overcoming the problem illustrated in <figref idref="DRAWINGS">FIGS. 2 and 3</figref>;

0021<figref idref="DRAWINGS">FIGS. 5 to 7</figref> are sectional views illustrating steps in <figref idref="DRAWINGS">FIG. 4</figref>;

0022<figref idref="DRAWINGS">FIG. 8</figref> is a flow chart illustrating a method for forming a via hole and a trench for a dual damascene interconnection consistent with the present invention;

0023<figref idref="DRAWINGS">FIGS. 9 to 13</figref> are sectional views illustrating steps in <figref idref="DRAWINGS">FIG. 8</figref>; and

0024<figref idref="DRAWINGS">FIG. 14</figref> is a flow chart illustrating another method for forming a via hole and a trench for a dual damascene interconnection consistent with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0025Systems and methods consistent with the present invention will now be described in detail with reference to the accompanying drawings. The following examples may be modified but do not limit the invention, which is set forth in the accompanying claims.

0026<figref idref="DRAWINGS">FIG. 8</figref> is a flow chart illustrating a method for forming a via hole and a trench for a dual damascene interconnection consistent with an embodiment of the present invention. <figref idref="DRAWINGS">FIGS. 9 to 13</figref> are sectional views illustrating the method of <figref idref="DRAWINGS">FIG. 8</figref>.

0027Referring to <figref idref="DRAWINGS">FIGS. 8 and 9</figref>, after an etch stop film <b>310</b> and an inter-metal insulating film <b>320</b> are sequentially formed on a lower metal film <b>300</b>, a via hole <b>330</b> through inter-metal insulating film <b>320</b> is formed, exposing a portion of a surface of etch stop film <b>310</b>. (Step <b>810</b>.)

0028Etch stop film <b>310</b> may comprise silicon nitride. A mask pattern (not shown) may be formed on inter-metal insulating film <b>320</b> for forming via hole <b>330</b>. Via hole <b>330</b> is formed by performing an etching process using the mask pattern. After forming via hole <b>330</b>, the mask pattern is removed.

0029Subsequently, a photoresist film <b>340</b> is formed on an entire surface such that via hole <b>330</b> is filled with photoresist <b>340</b> (Step <b>820</b>). Photoresist film <b>340</b> is formed with an ArF (having a wavelength of 193 nm), a KrF (having a wavelength of 248 nm) or an I-line (having a wavelength of 365 nm) light source and may have a dissolution rate of 0.1 to 10000 Å. When an ArF or KrF light source is used, a protection group of resin may be used to adjust the dissolution rate of photoresist film <b>340</b>. When an I-line light source is used, the dissolution rate of photoresist film <b>340</b> may be adjusted using an amount of Novolak resin and photo acid compound (PAC).

0030Next, as shown in <figref idref="DRAWINGS">FIG. 10</figref>, a top surface and a side surface of inter-metal insulating film <b>320</b> is exposed by recessing photoresist film <b>340</b> using a development process (Step <b>830</b>). The development process for photoresist film <b>340</b> can be performed using a basic solution having a concentration of 0.0001 to 100 N. The basic solution may contain tetramethyl ammonium hydroxide (TMAH) or KOH.

0031A recess depth d of photoresist film <b>340</b> from a surface of inter-metal insulating film <b>320</b> as shown in <figref idref="DRAWINGS">FIG. 10</figref> may have a maximum value of 90000 Å. The recess depth d can be adjusted by controlling the dissolution rate of photoresist film <b>340</b>. After performing the development process for photoresist film <b>340</b>, a rinse process using DI water is performed.

0032Next, as shown in <figref idref="DRAWINGS">FIG. 11</figref>, a bottom antireflective coating (BARC) film <b>350</b> is formed on the exposed surfaces of inter-metal insulating film <b>320</b> and photoresist film <b>340</b> (Step <b>840</b>). Next, a mask pattern <b>360</b> for trench formation is formed on BARC film <b>350</b> (Step <b>850</b>).

0033Subsequently, as shown in <figref idref="DRAWINGS">FIG. 12</figref>, a trench <b>370</b> is formed by performing an etching process using mask pattern <b>360</b> as an etch mask (Step <b>860</b>). Trench <b>370</b> is wider than via hole <b>330</b>.

0034Next, as shown in <figref idref="DRAWINGS">FIG. 13</figref>, photoresist film <b>340</b> within via hole <b>330</b> is removed (Step <b>870</b>). Mask pattern <b>360</b> is also removed simultaneously. Thereafter, BARC film <b>350</b> and a portion of etch stop film <b>310</b> exposed through via hole <b>330</b> are removed (not shown).

0035Consistent with the present invention, the recess process for photoresist film <b>340</b> (<figref idref="DRAWINGS">FIG. 10</figref> and Step <b>830</b>) is performed in a photolithography apparatus using the development process for the photoresist film. Consequently, a back side cleaning process is unnecessary and all processes can be performed in a single photolithography apparatus without the need to perform processes in several apparatuses alternately. In addition, defects can be further suppressed by performing the rinse process using DI water after performing the recess process.

0036<figref idref="DRAWINGS">FIG. 14</figref> is a flow chart illustrating a method for forming a via hole and a trench for a dual damascene interconnection consistent with another embodiment of the present invention.

0037As compared to the method of <figref idref="DRAWINGS">FIG. 8</figref>, the method of <figref idref="DRAWINGS">FIG. 14</figref> further includes performing an exposure process for photoresist film <b>340</b> (Step <b>830</b>′) prior to the development process at Step <b>830</b>. The exposure process for photoresist film <b>340</b> can be performed using a stepper or a scanner employing an I-line light source having a wavelength of 365 nm. The exposure process for photoresist film <b>340</b> need not use a reticle, and an entire surface of photoresist film <b>340</b> may be exposed.

0038The recess depth d of photoresist film <b>340</b> may be easily adjusted by controlling the amount of exposure in the exposure process at Step <b>830</b>′ and the development time in the process at Step <b>830</b>.

0039It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed structures and methods without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.